Abstract:The mechanism of fish swimming behavior and the influencing factors of swimming ability are hot issues in the current research of fish bionomics. Crucian carp, the typical Carangiform swimmer, was selected as the research object. Using numerical simulation method, dynamic grid technology combined with User-Defined Functions (UDF) to investigate the influence of the swimming ability of Crucian carp around the motion parameters, fish body size, and swimming environment (wall boundary), using the arrival dynamic and stable cruising speed of the bionic carp as a measure of the swimming ability of Crucian carp. The results show that when0.7≦f≦5.5，0.03≦a(x)max≦0.6, with the increase of frequency and amplitude, the time for the bionic carp to obtain dynamic stable cruise velocity is gradually shortened, and the cruise velocity increases accordingly. Crucian carp with different body sizes (length-to-thickness ratio) and body lengths were dimensionless and numerically calculated. It was found that the body size negatively correlated with swimming velocity when swimming forward with the same swing frequency and swing amplitude. A greater cruise velocity could be obtained when the length-thickness ratio was <0.166. Regarding body length, juvenile carp could reach the cruise stage more quickly but have a lower cruise velocity of about 0.6L/s. The speed of the bionic young fish is more significant in the acceleration stage, and the cruise stage is the same as the dynamic stable cruise velocity of the bionic adult fish, which is about 1L/s. The wall effect caused by the fish swimming near the wall can reduce swimming velocity. The effect of bilateral walls on the swimming velocity of bionic carp is more significant than that of unilateral walls, when the fish body is 0.5L from the one-side wall, and 0.8L from the bilateral wall will not be affected by the wall. The results can provide a valuable reference for fish bionomics research.